Answer: Betty's daughter is 34 years old now.
Explanation:
So Betty is currently 71. In three years, she will be 74. So she will be twice as old as her daughter at the age of 74. To find out how old Betty's daughter is in 3 years, I will divide 74 by 2, which is 37 (74/2). Finally, I will subtract the original 3 years from the 37 years of age of Betty's daughter, and I will get my answer for how old Betty's daughter is, which is 34 years old.